Influence of regional environmental variables on the radiative forcing of atmospheric microplastics

Atmospheric microplastics (AMPs) can absorb and scatter radiation, which can be quantified by radiative forcing. Although the radiative forcing of AMPs is commonly positive at the global scale, regional environmental variables affect the radiative forcing of aerosols, potentially reversing its directions and cause opposite radiative impacts in the atmosphere. In this study, the total suspended particles were collected within one year in Tianjin, China, and the monthly average concentration of AMPs of 200.0-463.9 items/m³ was detected. Accordingly, the direct radiative forcing (DRF) of AMPs was calculated as -0.03 to 0.03 W/m² at the top of the atmosphere and -0.09 to 0.72 W/m² at the Earth's surface, respectively. The surface albedo significantly affects the direction of the DRF of AMPs. A low surface albedo leads to a cooling effect of AMPs in the atmosphere in Tianjin, while a high surface albedo causes a warming effect in the atmosphere. The DRF calculated under different surface albedo indicates that the potential impact of AMPs on atmospheric temperature is relatively complex. The temperature changes caused by AMPs in grassland and bare soil areas may be opposite to those in areas covered by snow and ice.